In an electrical system including a signal source that produces an analog signal and a load circuit that delivers the analog signal out from the system analog signal processing is often needed in a signal path between the signal source and the load circuit. The signal source can be, for example, a power amplifier of a transmitter and the load circuit can be, for example, an antenna or a line transformer of the transmitter. The analog signal processing can comprise impedance transformation in order to match an output impedance of the signal source with an input impedance of the load circuit, filtering in order to modify a power spectrum of an output signal of the signal source, and phase shifting for e.g. signal level measurement purposes. For example, in a mobile communication device one or more of the following operations are needed: impedance matching on a signal path from a power amplifier to an antenna, filtering out harmonics of an output signal of the power amplifier, separating a received signal from a signal to be transmitted in order to provide a duplex communication channel, measuring an output power of the power amplifier, and/or performing antenna switching e.g. changing a position of the antenna from being connected to a transmitter to being connected to a receiver and vice versa.